The invention generally relates to ophthalmic lenses and, more particularly, the invention relates to ophthalmic lenses for increasing the depth of focus of the human eye.
It is well-known that the depth of focus of the human eye can be increased with the use of ophthalmic lenses with pinhole-like apertures substantially near the optical center of the lens. For example, U.S. Pat. No. 4,976,732 (xe2x80x9cthe ""732 patentxe2x80x9d) discloses an ophthalmic lens with a pinhole-like aperture. In the ""732 patent, a mask forms the pinhole-like aperture. In one embodiment, the mask is circular in shape. When the pupil is constricted, light enters the retina through the pinhole-like aperture. When the pupil is dilated, light enters the retina through the pinhole-like aperture and the outer edges of the mask.
In addition, U.S. Pat. No. 3,794,414 (xe2x80x9cthe ""414 patentxe2x80x9d) discloses a contact lens with a pinhole-like aperture. In the ""414 patent, the mask forming the pinhole-like aperture has radial slits and/or scalloped edges. In addition, the mask forming the pinhole-like aperture is two spaced-apart concentric circles. However, the radial slits, scalloped edges and two spaced-apart concentric circles promote light diffraction, which in turn reduces the contrast of the image.
In U.S. Pat. Nos. 4,955,904, 5,245,367, 5,757,458 and 5,786,883, various modifications to an ophthalmic lens with a pinhole-like aperture are disclosed For example, the patents disclose use of an optical power for vision correction in the pinhole-like aperture, or use of an optical power for vision correction in the area outside the mask. In contrast, in U.S. Pat. No. 5,980,040, the mask is powered. In particular, the mask is powered to bend the light passing through the mask to impinge on the retina at a radial distance outside of the fovea. In other words, the mask is powered to xe2x80x9cdefocusxe2x80x9d the light.
In each of these patents, the mask forming the pinhole-like aperture is made, in whole or in part, of a light absorptive material. A light-absorptive material is a material in which light is lost as it passes through the material, generally due to conversion of the light into another form of energy, e.g., heat.
In accordance with an embodiment of the invention, an ophthalmic lens comprises a lens body, an optic located in the lens body, the optic configured to produce light interference, and a pinhole-like optical aperture substantially in the center of the optic. In a further embodiment of the invention, the optic is configured to positively interfere with parallel light reaching the optic and negatively interfere with diverging light reaching the optic. In addition, some diverging light may pass through the optic. In this alternate embodiment of the invention, the optic is configured to spread out the diverging light passing through the optic.
In an alternate embodiment of the invention, an ophthalmic lens comprises a lens body, an optic located in the lens body, the optic configured to produce light scattering, and a pinhole-like optical aperture substantially in the center of the optic. In a further embodiment of the invention, the optic is configured to forward scatter parallel light reaching the optic and back scatter diverging light reaching the optic.
In another alternative embodiment of the invention, an ophthalmic lens comprises a lens body, an optic located in the lens body, the optic configured to produce light reflection, and a pinhole-like optical aperture substantially in the center of the optic. In an alternate embodiment of the invention, the optic is composed, in whole or in part, of a light reflective material.
In further embodiments of the inventions, the optic may be configured as a series of concentric circles, a weave, a pattern of particles, or a pattern of curvatures. In addition, the pinhole-like aperture includes an optical power for vision correction, and may have a diameter in the range of substantially 0.05 mm to substantially 5.0 mm. Further, the optic may have an outer diameter in the range of substantially 1.0 mm to substantially 8.0 mm. The optic may also be composed of a material having varying degrees of opacity, and the ophthalmic lens and the optic may be composed of a bio-compatible, non-dissolving material, such as polymethyl methacrylate or a medical polymer.
In accordance with another embodiment of the invention, a method for screening a patient for an ophthalmic lens, the ophthalmic lens having a pinhole-like optical aperture, comprises fitting each of the patient""s eyes with a first contact lens, placing a mask on each of the first contact lens, the mask configured to produce a pinhole-like aperture in each of the first contact lens, fitting each of the patient""s eyes with a second contact lens, the second contact lens being placed over the mask to hold the mask in a substantially constant position, and testing the patient""s vision.
In further embodiments of the invention, the mask may be a light interference mask, a light scattering mask, or a light reflective mask. The first contact lens may include an optical power for vision correction. In addition, each of the first and second contact lenses may be soft contact lenses. Further, the mask for each of the patient""s eyes may have a light absorption of substantially 100%. In the alternative, the mask for each of the patient""s eyes may be composed of a polarized material.
In still further embodiments of the invention, the process of testing comprises testing the patient""s acuity for distance vision under bright and dim lighting conditions, testing the patient""s acuity for near vision under bright and dim lighting conditions, and testing the patient""s contrast sensitivity under bright and dim lighting conditions. The process of testing may further comprise testing a patient""s visual acuity using a night driving simulation. The night driving simulation may include a series of objects and road signs under bright and dim lighting conditions, as well as having the patient face a simulated oncoming automobile headlight.
In an alternate embodiment of the invention, the process of testing comprises replacing the mask in one of the patient""s eyes with a mask having a light absorption of substantially 85% or less, then, if needed, replacing the mask in the patient""s other eye with a mask having a light absorption of substantially 85% or less. Further, the process of testing comprises, if needed, removing the mask from one of the patient""s eyes.
In another alternate embodiment of the invention, the process of testing comprises placing an analyzer in the spectacle plane of one of the patient""s eyes, the analyzer including a polarizing element, rotating the polarizing-element to achieve an optimal balance of contrast and brightness, and determining the resultant light absorption of the mask. In addition, the process of testing may include evaluating the cosmetic appearance of the mask.
In accordance with a still another embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises removing the epithelial sheet, creating a depression in the Bowman""s membrane, the depression being of sufficient depth and width to expose the top layer of the stroma and accommodate the mask, placing the mask in the depression, and placing the removed epithelial sheet over the mask. In a further embodiment of the invention, the depression may extend into the top layer of the stroma.
In an alternate embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises hinging open a portion of the Bowman""s membrane, creating a depression in the top layer of the stroma, the depression being of sufficient depth and width to accommodate the mask, placing the mask in the depression, and placing the hinged Bowman""s membrane over the mask.
In another alternate embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises creating a channel in the top layer of the stroma, the channel being in a plane parallel to the cornea""s surface, and placing the mask in the channel. In this embodiment, the mask may be threaded into the channel, or the mask may be injected into the channel.
In still another alternate embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises penetrating the top layer of the stroma with an injecting device, and injecting the mask into the top layer of the stroma with the injecting device. In this embodiment, the injecting device may be a ring of needles. In addition, the mask may be a pigment, or the mask may be composed of pieces of pigmented material suspended in a bio-compatible medium. The pigmented material may be made of a medical polymer, e.g., suture material.
In one other alternate embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises hinging open a corneal flap, the corneal flap comprising substantially the outermost 20% of the cornea, placing the mask on the cornea, and placing the hinged corneal flap over the mask.
In still one other alternate embodiment of the invention, a method for implanting a mask in a cornea, the mask configured to increase the depth of focus of the human eye, comprises creating a pocket in the stroma, the pocket being of sufficient size to accommodate the mask, and placing the mask in the created pocket.
In further embodiments of the inventions, the mask.may be a light interference optic, a light scattering optic, or a light reflective optic. In addition, the mask may block visual aberrations. In addition, after surgery, a contact lens may be placed over at least the affected portion of the cornea.